Tuning mechanism



Nov. 21, 1950 M. J. PIFER ETAL TUNING MECHANISM 3 Sheets-Sheet 1 Filed April 10, 1948 INVENTOR 7770712712 JR'f'er,

Nov. 21, 1950 M. J. PIFER ETAL 2,530,663

TUNING MECHANISM Filed April 10, 1948 5 Sheets-Sheet 2 INVENTOR Marta 06/517 .2. 7776:5 62

ATTORNEY Nov. 21, 1950 M. J. PIFER ETAL 2,530,663

TUNING MECHANISM Filed April 10, 1948 3 Sheets-Sheet 5 INVENTOR 7a n'onJE/ r', (((vnzD. 7776396? and 1 07 777 6 02 09 ATTOF-2NEY Patented Nov. 21, 1950 UNITED STATES PATENT OFFICE Kenmore, and Harold J. McGarvey, Buffalo, N. Y., assignors to Colonial Radio Corporation,

Buffalo, N. Y.

Application April 10, 1948, Serial No. 20,348

8 Claims.

This invention relates to a push-lock tuner mechanism for tuning radio receivers, and, more particularly, to such mechanism employing socalled piano key station selectors, rather than conventional push buttons.

It is an object of this invention to provide mechanism of the class described, in which individual keys may be set to select a particular station as desired, with a high degree of repeat accuracy and relatively free from inaccuracies ordinarily introduced by wear.

It is 'a further object of this invention to provide such mechanism in which the selector keys can be reset from one station to another without complicated adjustment and without the use of any tools.

It is a further object of this invention to provide such mechanismin which excessive pressure on the key is not required either to lock or unlock the adjustment of the individual station selector when recalibrating the key from one station to another.

It is a further object of this invention to provide mechanism which does not require extreme tolerances in manufacture, and one in which the various components of the mechanism are easily and cheaply formed by the use of punch press parts, and relatively easily, quickly, and cheaply assembled.

It is a further object of this invention to provide mechanism with a high degree of repeat accuracy for selected stations and one which the ordinary user can easily and quickly recalibrate or reset individual keys from one station to another.

Still other objects and advantages of our invention will be apparent from the specification.

In the specification we have explained the principles of our invention and the best mode in which we have contemplated applying those principles, so as to distinguish our invention from other inventions, and we have particularly pointed out and distinctly claimed the part, improvement, or combination which we claim as our invention or discovery.

The features of novelty which we believe to be characteristic of our invention are set forth with particularity in the appended claims. Our invention itsef, however, both as to its fundamental principles and as to its particular embodiments, will best be understood by reference to the specification and accompanying drawing, in which vFigure 1 is afront elevation of tuner mechanism in accordance with our invention ready to be installed in a radio receiver,

Figure 2 is an end view of the tuner shown in Figures 1 ad 2,

Figure 3 is a section on line 3-3 of Figur 1,

Figure 4 is a diagrammatic view of a single selector key and its associated mechanism in the normal or unactuated position,

Figure 5 is a view simila rto Figure 4, showing the mechanism of Figure 4 in the position it assumes after the station selector key has been pressed to select the station,

Figure 6 is a top plan view of the key mechanism of Figures 4 and 5,

Figure 7 is a detailed side elevation View of the cam end of the key mechanism of Figure 4, with part of the mechanism removed to show the construction,

Figure 8 is a similar view of the front end of the mechanism of Figure 4,

Figure 9 is a view similar to Figures 4 and 5, but showing the mechanism in the position it assumes when the key is lifted to unlock the cam preparatory to recalibrating the key to select another station, and

Figure 10 is a view similar to Figure 5, but showing a modified form of mechanism.

Forpurposes of clarity of explanation, it is believed desirable first to discuss the nature of the tuner generally without reference to details of the drawing. As already stated, the selector keys are preferably made in the form of what is termed piano keys, rather than push buttons. That is to say, instead of being plungers which are moved in and out, the keys are mounted side by side on a shaft with projecting ends which may be engaged by the operator and pressed down to select the station or calibrate the particular key for future use, and lifted up to unlock the adjustment preparatory to recalibration.

As will be understood, the tuning instrumentality may be any type such as a variable condenser, permeability tuner, or the like, the position of which is determined by the angular position of a control shaft. For purposes of simplicity, and because the specific form of condener or permeability tuner forms no part of this invention, the same is not shown in detail, and is indicated only by the control shaft, or so-called tilt bar. The angular position of the tilt bar is determined by a so-call ed rocker arm, consisting of an arcuate shaped cam which engages both sides of the tilt bar, and sets it to the proper position in accordance with previous calibration. This cam-carrying arm is generally known as a rocker arm, and when any station selector key is depressed to select the desired station corresponding thereto, in accordance with our invention, the rocker arm is given a slight rotation, carrying the cam into contact with the tilt bar, and setting the tilt bar into desired position.

In accordance with out invention, the cam is adjustably mounted on the rocker arm, and is provided with mechanism for clamping the cam in the desired position. This clamping mechanism also has operating mechanism mounted on the rocker arm for cooperation with the key in such a manner that raising the key above its normal position unlocks the cam, permitting it to be reset to a new position, and depressing the 1;

key locks the cam in the new position without the use of any tools, and without requiring any operation except that which the user would make in tuning the station manually.

Referring now more particularly to Figure 1,

the tuner mechanism is generally enclosed in a casing preferably of sheet metal and having extending therefrom a row of selector keys I arranged horizontally across the front of the container. The individual keys may be of the form shown in Figure 2, having a flat upper surface or any other suitable surface adapted to be pressed by the operators finger, and having a lower surface conveniently shaped to enable the operator to lift the key when it is desired to recalibrate it.

' station for which each key is calibrated.

Each key 8 is mounted on shaft 2 and has a central slot to permit the mounting of key arm or rocker arm 5, and the key pawl 3, both of which are mounted side by side upon shaft 2 within the opening in key 1. The lower portion of key pawl 3 carries a finger 3a projecting forwardly under the key l, and arranged to be struck by the operating surface la of the key. The rocker or key arm 5 carries a vertical portion 5a projecting above shaft 2 and partially behind key pawl 3 as shown in Figure 8, and a compression spring is mounted to bear on the left hand ear of a cut out in key pawl 3, and similar ear projecting to the left from the vertical portion key pawl 5a of key arm 5. By reason of this construction, it will be seen that pressure downwardly upon the key I causes contact between key I and arm 3a of the key pawl 3, rotating the same clockwise, thereby pressing spring 1 and rotating rocker or key arm 5 clockwise. This rotates the entire rocker bar mechanism from the position view shown in Figure 4 to that shown in Figure 5, during the course of which the ends 8a and 8b of the cam or rocker 8 engage the opposite extending portions 9a and 9b of the tilt bar 9, mounted on shaft l0, rotating it to a final position determined by tht setting of the adjustable cam 8 on the rocker arm 5. Shaft IE3, as will be understood, may be geared or otherwise suitably connected to any desired tuning instrumentality, such as a variable condenser, shown in Figure 3.

It will be understood that each one of the selector keys may be arranged as just described, so that each one may be previously calibrated for a particular station. It will be noted that as tht key and rocker bar move from the position shown in Figure 4 to that shown in Figure 5, latch 2 i, which extends across all the key pawls, pivoted on shaft 22, is first lifted by the edge portion 30 at the top of key pawl 3, and thereafter, as the edge portion 30 rides under the lip of the latch, the same finally drops into notch 3d, latching the key in depressed position, and holding the tuner in the desired position until another key is depressed. If this be done, the first effect is to lift the latch 2|, rotating it slightly counterclockwise, and releasing the key pawl 3, permitting spring 6 to return rocker bar 5, key pawl 3 and key i to initial position; thus a depression of any key releases the first key.

Atttention is invited at this point to the fact that the final seat of the cam 8 on the tilt bar 9 is maintained by the spring pressure of the compression spring Depressing the key I by over travel simply increases the compression load on spring 4i, and takes up an excess of motion, which might otherwise tend to bend rocker arm 5, earn 8, or tilt bar 9. It Will also be noted that when the operators finger is removed from the key, the rocker bar maintains the cam 8 against tilt bar 9 by the pressure of spring 4. This tends to compensate for wear and insures a high degree of repeat accuracy of subsequent tunings. In general, the operation thus far described will be easily and readily understood by anyone familiar with the operation of conventional rocker and tilt bar tuners, and with this operation understood, we now turn to the construction and operatiton of the mechanism which includes the pushlock features, by means of which cam 8 may be adjusted and locked in position to select any desired station, without the use of tools.

The cam 8, as will be observed particularly from Figure 7, is arcuate shaped and rests in an arcuate seat at the upper end of rocker arm 5, and is secured therein by a yoke H consisting of front plate Ma and back plate lib embracing rocker arm 5 and connected by a small web portion He. The front and back plates Ha and Hi) each have outwardly projecting ears lld and tie, and the yoke H is pivotally mounted at its upper right hand side on the upper portion of rocker arm 5, as by pivot 12 projecting through openings in the yoke H and in the rocker arm 5, and secured therein in any suitable fashion. The purpose of the yoke H is to clamp the cam 8 in adjusted position. This clamping is produced by applying a torque tending to rotate the yoke ll about the pivot l2 in a counterclockwise direction, causing the connecting portion lic to hold the cam 8 securely in its seat. So long as this pressure is applied, the cam is held tightly in its seat, but in order to adjust the cam, this pressure must be released.

How this pressure may be applied and released will now be described. Secured on each outer face of the yoke H, in this embodiment of the invention, we provide a pair of springs I 31 and E32, these springs being generally in the shape of a C, and being provided at the left hand end with a siot to receive the ear I id, and with a face to engage the ear I le. The springs are placed in position by slightly spreading them, sliding them in position and allowing them to snap against the ears lie and lid by the natural resiliency of the metal. The right hand end of the spring I31 is secured to the end of link M1 on the forward face of rocker arm 5, and the corresponding portion of the rear spring 132 is similarly secured to a similar link I42 on the rear face of rocker arm 5.

By the use of the preloaded springs I3, which in the embodiment of the invention now described are preloaded to a pressure of about 100 pounds exerted between ears Nd and He, it is possible to obtain high locking pressure on cam 8 with comparatively little motion of links I41 and I42.

The forward ends of links I41 and I42 are secured together. by a pin I6 extending through them, and through a triangular hole in rocker arm 5, best seen in dotted lines in Figure 8. A toggle bar I? lies within the triangular opening in rocker arm 5 and serves to control the motion of pin I6. The key I carries a bifurcated arm Id, engaging pin I6 between its bifurcations. When the key I is slightly lifted with key pawl latched by latch 2|, pin I6 is forced downwardly, and

slightly rearwardly by the front wall of the tri angular hole in rocker arm 5. At the same time, the rearward motion is controlled by toggle arm I! pivoting about the rear corner of the triangular hole, and the result of this is that links Mr and I42 are given a slight rearward motion with respect to rocker arm 5 which in turn is applied to springs I31 and I32 through eccentric I5, secured on links I41 and I42, and engaging the right hand end of springs I31 and I32. These springs in turn apply a rearward push to the ears IId at the rear face of the yoke II, and thereby produce a slight rotation of the yoke II around pivot I2 in the clockwise direction, removing the pressure holding earn 8 in its seat and permitting the cam to slide freely.

When it is desired to reset or recalibrate the cam 8 to select a different station, key I is first depressed to the full clockwise rotation, just as in selecting a station, at which point key pawl 3 is latched in clockwise position by latch III at 3d. Key I may then be lifted or rotated counterclockwise to the full extent of its motion, until pin 3| is forced downwardly and rearwardly as already described, unlocking cam 8 in its seat.

The receiver may now be tuned manually, setting tilt bar 9 to the correct position for the new station. Key I is now depressed, engaging pin I 6 and moving it upward and forward. This motion, applied to yoke II by links I61 and I42 and springs I31 and I32, slightly rotates yoke II on pivot I2 and clamps cam 8 in the new position.

In order to prevent accidental unlocking of the cam when the key returns to its normal position, the key is provided with an extension Ib carrying a leaf spring 23, secured thereto as by rivets 24, and engaging a detent 25. This construction offers sufficient resistance to counterclockwise rotation of key I to prevent the key accidentally rotating far enough to unlock the cam, at the same time permitting such rotation when additional pressure is applied intentionally by the operator.

To provide initial adjustment of the point of lock up of cam 8 in its seat, adjustability of the point of connection between springs I31 and I32 and links I41 and I42 is provided by mounting eccentric stud I5 on these links, the same passing through holes in springs I31 and I32, links I41 and I42, and through a clearance slot in rocker arm 5, and being secured in adjusted position by washer I8 and lock washer I9 and nut 20. If desired, a small spot of solder may al o be applied to the eccentric and link after the correct adjustment has been determined by rotating the eccentric stud, which passes through an opening in the lower right hand end of springs I31 and I32. To prevent accidental disengagement of springs I31 and I32 from the eccentric stud I5, the ears I Ie may be bent downwardly to hold the springs in position as indicated in Figure 9. A positive stop to the upward motion of th keys may be provided as by bar I which is engaged by spring 23, when the key reaches the end of its travel.

The modification shown in Figure 10 is essentially the same in principle as the embodiment already described, but differs therefrom in that the lock up apparatus is considerably simpler, consisting of fewer parts. In this instance, clamping arm 30 is secured in position by pivoting at point I2 on the rocker arm 5. The arm 30 combines in one part the yoke II and links I41 and I42, the arm 30 consisting as shown of two substantial horizontal portions connected by a vertical portion, and consisting of two similar parts 301 and 302 lying On both sides of rocker arm 5 and connected by an intermediate portion or neck 303. The upper portions of arms 391 and 302 and the connecting portion 303 serve to hold the cam 8 in its seat, the cam and seat being the same as before.

The right hand extremities of arms 391 and 302 are connected together by means of pin 3| passing through an arcuate clearance slot 302 in rocker arm 5, having a high portion 33 and the pin 32 is engaged by the bifurcations of arm Id as before.

Operation is not greatly different from that already described. In the position shown in Figure 10 with the lever 33 at the clockwise eXtren ity of its rotation, cam 8 is free to slide in its seat. and may be adjusted. When it is desired to recalibrate the cam to a different station, key I is latched in the clockwise position and held by latch 2I, the key is then lifted or rotated counterclockwise until pin 3I is lowered beyond raised portion 33 and unlocks cam 8. The receiver may now be tuned manually, setting the tilt bar 9 to the correct position for the new station. If key I is now depressed, engaging pin 3I moving it upward and rotating arm 30 slightly counterclockwise. beyond raised portion 33, cam 8 will be locked in the new position.

While we have shown and described certain preferred embodiments of our invention, it will be understood that modifications and changes may be made without departing from the spirit and scope thereof, as will be clear to those skilled in the art.

We claim:

1. In mechanism of the class described, a control shaft to be set to predetermined angular positions and having lateral extensions to be engaged by a positioning element, a positioning element having an arcuate base concentric with said shaft when said element is fully engaged with said shaft and said shaft is in the position determined by engagement with said element, and a rocker arm carrying said element, said arm having an arcuate seat of the same radius as said arcuate base and concentric therewith, clamping mechanism carried by said rocker arm for securing said element in desired position on said rocker arm, a shaft on which said rocker arm is mounted, and behind which said element projects, and an operating lever pivotally mounted on and extending forward of said last mentioned shaft and operatively connected to said rocker arm to rock said rocker arm when said lever is depressed, and a connection between said clampingmechanism and said operating lever for re- 7 ieasnig said cramping mechanism: said op= crating lever is raisedabove the position it oc cupie's when not depressed to actuate said rocker arm.

2. In mechanism of the class described, a con-" trol shaft to be set to predetermined angular positions and having lateral extensions to be en'- sfl-ged by a positioning element, a positioning element having an areuate base concentric with said shaft when said element is fully engaged with said shaft and said shaft is in the position determined by engagement with said element, and a rocker arm carrying said element, said arm having an arcuate seat of the same radius as said arcuate base and concentric therewith, and clamping mechanism carried by said rocker arm for securing said element in desired position on said rocker arm, a shaft on which said rocker arm is mounted, and behind which said element projects, and an operating lever extending forward of said shaft for rocking said rocker arm and for operating said clamping mechanism, said operating lever having means for unlocking said clamping mechanism on rotation in one direction, and for fully engaging said positioning element and said shaft and for causing securing of said clamping mechanism on rotation in the other direction.

3. In mechanism of the class described, a control shaft to be set to predetermined angular position, and having lateral extensions to be engaged by a positioning element, a positioning element, a rocker arm having a seat for mounting said positioning element, a shaft upon which said rocker arm is mounted, a ke pivotally mounted on said last mentioned shaft for rotation in either direction operatively connected to said rocker arm and causing rotation of said rocker arm to engage and position said control shaft on rotation of said key in one direction, clamping means for holding said positioning element and an operating connection between said clamping means and said key, said connection moving said clamping means in a direction to release said positioning element when said key is rotated above neutral position and in a direction to clamp said positioning element when said key is rotated back to neutral position.

4'. In mechanism of the class described, a control shaft to be set to predetermined angular positions, and having lateral extensions to be engaged by a positioning element, a positioning element, a second shaft, a rocker arm mounted on said shaft and carrying said positioning element, a key pivotally mounted on said second shaft for rotation in opposite directions, said key being operatively connected to said rocker arm so as to rock said rocker arm when said key is depressed, a yoke pivotally mounted on said rocker arm for clamping said positioning element, and an operating lever extending from said yoke toward said key and an operating connection between said operating lever and said key, said connection moving said operating lever in a direction to move said yoke to unclamp said positioning element when said key is raised above neutral position, and to move said yoke in a direction to clamp said positioning element when said ke is returned from raised to neutral position.

5. In mechanism of the class described, a control shaft to be set to a predetermined angular position, and having lateral extensions to be an gages by a positioning element, a positioning element, a rocker arm having an arcuate seat for mounting said positioning element, said. positioning element having an arcuate base for engagingsaid ar cuate seat, andclamping mechanism mounted on said rocker for securing said positioning. element in position in said seat, said clamping mechanism comprising a yoke: pivotal-ly mounted on said rocker arm and. arranged to press said positioning element into its seat, a key rotatable in opposite directions, and an operative connection between said key and said yoke for clamping and releasing said positioning element on rotation of said key in opposite directions, said last mentioned connection including a preloaded spring interposed between said yoke and said key.

6. In mechanism of the class described, a control shaft to be set to predetermined angular positions, and having lateral extensions to be engaged by a positioning element, a positioning element, a second shaft, a rocker arm mounted on said shaft and carrying said positioning element, a key mounted on said second shaft for rotation in opposite directions, a yoke pivotally mounted on said rocker arm for clamping said positioning element, and an operating lever extending from said yoke toward said key and engageable by said key to effect clamping and unclamping of said element on rotation of said key in opposite directions, said last men tioned connection including a preloaded spring connected to said yoke and. interposed between said yoke and said operating lever.

7. In mechanism of the class describeda control shaft to be set to predetermined angular positions, and having lateral extensions to be engaged by a positioning element, apositioning element, a second shaft, a rocker arm mounted on said shaft and carrying said positioning element, a key mounted on said second shaft for rotation in opposite directions, a yoke pivotally mounted on said rocker arm for clamping said positioning element, and an operating lever extending from said yokev toward said key and en-- REFERENCES CITED The following references are. of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,230,852 Teaf et a1 Feb. 4,1941 2,263,434 Bentonet al. Nov. 18,1941 2,301,090 Teaf s Nov. 3; 1942 

